Magnetic memory disk substrates

The glass-ceramic also demonstrates a high strain point (temperature resistance) of more than 1000°C. This property is particularly important in the fabrication of various types of substrates, such as that of the magnetic 

High modulus is important, e.g., E = 2.1 X 10 psi (14.5 GPa), because stiffness prevents flutter of the magnetic memory disk at high rotational speeds, e.g., 5000-10,000 rpm. 

Pure spinel glass-ceramics show other properties distinct from enstatite-spinel glass-ceramic. These include spinel glass-ceramics and are characterized by GTE of 3.4 X 10 K (0 C-300°C) and transparency in the visible spectrum. They are also suitable for the production of highly pol-ishable disk substrates (Fig. 4-5) (Pinckney 1999). 

The canasite glass-ceramic demonstrates high fracture resistance, which is favorable for the disk substrate application, in addition to a number of other favorable properties compared with standard nickel phosphide-coated aluminum ceramic substrate materials. These properties are  

All four types of glass-ceramics (spinel-enstatite, spinel, lithium disilicate, and canasite) have been produced by Corning Inc., USA. 

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An ultraprecision lapping on magnetic memory disk substrate of glass by fixed abrasives in newly developed microspherical cell Yoji Tomita, Tanaka Co. Ltd, Japan and Hiroshi Eda, Ibaraki University, Japan... 

Figure 4-5 Spinel-enstatite glass-ceramic as a magnetic memory disk substrate, in comparison to a canasite disk and a nickel-spinel glass-ceramic.

Electrically Functional. Refractory coatings are used in semiconductor devices, capacitors, resistors, magnetic tape, disk memories, superconductors, solar ceUs, and diffusion barriers to impurity contamination from the substrate to the active layer. 

Beall G.H., "Magnetic Memory Storage Device and Disk Having a Glass-Ceramic Substrate," U.S. Pat. No. 5 744 208, 1998. 

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